But scientists are now following a rise in cases caused by the closely related BA.2. It is being called a sub-variant of Omicron. It is starting to overtake BA.1 in parts of Europe and Asia.
但是科学家现在正在关注密切相关的BA.2导致的病例增长。它被称为奥密克戎的子变种。它开始在欧洲和亚洲的部分地区超过BA.1。
A sub-variant of the new coronavirus
新冠病毒的子变种
Worldwide, BA.1 has been linked to more than 98 percent of cases that had genomes sequenced, reported GISAID on January 25. GISAID is an international science organization that studies and releases scientific information about viruses.
GISAID于1月25日报告称，全球范围内98%经过基因测序的病例都与BA.1有关。GISAID是一家研究与发布病毒相关科学信息的国际科学组织。
But several countries are reporting increases in the sub-variant known as BA.2, the World Health Organization (WHO) reported. BA.2 does not cause more severe illness than BA.1, the WHO also said.
但是世卫组织报告称，一些国家报告的BA.2子变种有所增长。世卫组织还表示，BA.2不会引发比BA.1更严重的疾病。
In addition to BA.1 and BA.2, the WHO lists two other Omicron sub-variants BA.1.1.529 and BA.3. All are closely related genetically. But each has a mutation that could affect how it behaves.
除了BA.1和BA.2，世卫组织还列出了奥密克戎另外两个子变种BA.1.1.529和BA.3。所有这些子变种都在遗传上密切相关。但是各自都存在可能影响其行为方式的突变。
Trevor Bedford is a virologist at Fred Hutchinson Cancer Center in Seattle, Washington. He has been studying the variants of the new coronavirus.
特雷弗·贝德福德是华盛顿州西雅图市弗雷德哈钦森癌症中心的病毒学家。他一直从事新冠病毒变种研究。
He wrote on Twitter recently that BA.2 makes up about 82 percent of cases in Denmark, 9 percent of the cases in Britain and 8 percent in the United States. These percentages come from his examination of the genome sequencing information provided by GISAID as well as information from the University of Oxford.
他最近在推特上写道，BA.2约占丹麦病例的82%，英国病例的9%，以及美国病例的8%。这些百分比来自于他对GISAID提供的基因测序信息以及牛津大学提供信息的审查。
Omicron's BA.1 variant has been somewhat easier to follow than earlier variants. That is because BA.1 is missing one of three important genes contained in earlier variants. For this reason it can be easily identified.
奥密克戎BA.1变种比早期的变种更容易追踪。这是因为BA.1缺少早期变种的三个重要基因中的一个。因此它很容易被识别出来。
BA.2 is sometimes called a "stealth" sub-variant. It does not have the same missing gene. Instead, scientists are following it the same way they have followed earlier variants, including Delta. They do this by counting the number of virus genomes given to organizations such as GISAID.
BA.2有时候被称为隐形子变种。它不存在相同的缺失基因。取而代之的是，科学家正在按照追踪包括德尔塔在内的早期变种的方式来追踪它。他们通过提供给GISAID等机构的病毒基因组数量来实现这点。
As with other variants, an infection with BA.2 can be confirmed by using coronavirus home tests. Experts, however, have said that the home tests cannot identify which variant is responsible for an infection.
与其它变种一样，BA.2感染可以通过采用新冠病毒族谱测试来确认。然而专家表示，族谱测试无法确定导致感染的变种。
More infectious?
更具传染性？
A Danish study reports that BA.2 is more infectious than BA.1, and is able to infect those who are vaccinated, but it does not cause more severe illness.
丹麦的一项研究报告称，BA.2比BA.1更具传染性，它能感染接种过疫苗的群体，但是不会导致更严重的疾病。
In England, the UK Health Security Agency studied contact information for people infected with COVID-19 from December 27, 2021, through January 11, 2022. The Agency suggested that transmission within homes is a little higher among people infected with BA.2. That rate was around 13 percent. With Omicron cases the infection rate was 10 percent. There appears to be no difference in vaccine effectiveness.
在英格兰方面，英国卫生当局研究了2021年12月27日至2022年1月11日期间感染新冠病毒人群的联系信息。该机构表示，在感染BA.2的人群当中，家庭传播率略高。这个比例大约为13%。奥密克戎病例的感染率为10%。疫苗有效率似乎没有差别。
The important question is whether people who were infected with the BA.1 will be protected from BA.2, said Dr. Egon Ozer. He is an infectious disease expert at Northwestern University Feinberg School of Medicine in Chicago.
艾根·奥泽尔博士表示，最重要的问题是，BA.1的感染者是否会对BA.2免疫。他是芝加哥市西北大学范伯格医学院的传染病专家。
In Denmark, some places that had a high number of cases of BA.1 were reporting rising cases of BA.2, Ozer said.
奥泽尔表示，在丹麦，一些BA.1病例数较多的地区报告的BA.2病例数正在上升。
If BA.1 infection does not protect against BA.2, it could create another round of infections.
如果BA.1感染不能预防BA.2，它可能会造成新一轮感染。
"It's too early to know if that will happen," Ozer said.
奥泽尔表示：“现在判断这是否会发生尚为时过早。”
The good news, he said, is that vaccines and booster shots still "keep people out of the hospital and keep people from dying."
他说，好消息是疫苗和加强针仍然能让人们避免住院和死亡。